The Optolong Clear Focusing Filter is designed to pass the visible spectral range between 420-680nm with 98.5% transmission.
The use of filters for astrophotography, especially narrowband filters, often results in blurry images that are difficult to focus. A clear filter such as the Clear Focusing Filter from Optolong can be used to focus the image precisely. Image sharpness is improved. When used with astro-modified DSLRs, the filter ensures higher efficiency and sensitivity. It also acts as an excellent dust cover, preventing dust from settling on the lens during long exposures.
